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Automating Manufacturing Systems - Process Control and ...

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continuous actuators - 24.3<br />

comm<strong>and</strong><br />

generator<br />

(e.g., PLC)<br />

desired position<br />

or velocity<br />

controller<br />

voltage/<br />

current<br />

power<br />

amp<br />

amplified<br />

voltage/<br />

current<br />

motor<br />

encoder<br />

Figure 24.1<br />

A Typical Feedback Motor <strong>Control</strong>ler<br />

24.2.1 Basic Brushed DC Motors<br />

In a DC motor there is normally a set of coils on the rotor that turn inside a stator<br />

populated with permanent magnets. Figure 24.2 shows a simplified model of a motor. The<br />

magnetics provide a permanent magnetic field for the rotor to push against. When current<br />

is run through the wire loop it creates a magnetic field.<br />

I<br />

I<br />

magnetic<br />

field<br />

axis of<br />

rotation ω

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